package au.gov.amsa.navigation;
   
   public class Mmsi implements Identifier {
   
       private final int mmsi;
       private final int hashCode;
   
       public Mmsi(int mmsi) {
           this.mmsi = mmsi;
          this.hashCode = calculateHashCode();
      }
  
      public int value() {
          return mmsi;
      }
  
      @Override
      public long uniqueId() {
          return mmsi;
      }
  
      private int calculateHashCode() {
          final int prime = 31;
          int result = 1;
          result = prime * result + (mmsi ^ (mmsi >>> 32));
          return result;
      }
  
      @Override
      public int hashCode() {
          return hashCode;
      }
  
      @Override
      public boolean equals(Object obj) {
          if (this == obj)
              return true;
          if (obj == null)
              return false;
          if (getClass() != obj.getClass())
              return false;
          Mmsi other = (Mmsi) obj;
          if (mmsi != other.mmsi)
              return false;
          return true;
      }
  
      @Override
      public String toString() {
          return "Mmsi [mmsi=" + mmsi + "]";
      }
  
  }